Liquefied gas evaporator



O. L. GARRETSON LQUEFIED GAS EVAPORATOR July 24,.-` 1951 Filed Dec,INI/ENTOR. n OLGARRETSON Patented July 24, 1951 2,561,506 LIQUEFIED GASEVAPORATOR Owen L. Garretson, Bartlesville, Okla., assignor to PhillipsPetroleum Company, a corporation of Delaware Application December 29,1945, Serial No. 638,406

6 Claims. (Cl. 62-1) This invention relates to evaporators. In one ofits more specific aspects it relates to an evaporator for use intransforming liquefied petroleum gases to their normally gaseous statesin which condition the gases are in condition for use as fuel.

Liqueable petroleum gases are transported,

and stored under pressure as liquids because of the relatively smallvolume occupied by a liquid in comparison to its gaseous volume. Suchfuels must be in the form of gas in order to be mixed with air forcombustion. The apparatus of my invention is particularly useful inserving as an evaporator for transforming liqueed petroleum gases totheir gaseous forms.

An object of my invention is to provide an evaporator apparatus suitablefor use in evaporating liqueed normally gaseous materials.

Another object of my invention is to provide an evaporator suitable foruse in evaporating liquefied petroleum gases.

Still other objects and advantages of my invention will be apparent tothose skilled in the art from a careful study of the followingdisclosure which, taken in conjunction with the attached drawing,respectively describes and i1- lustrates a preferred embodiment of myinvention.

The drawing shows, in section, one form of my evaporator. i

Referring to the drawing, the evaporator is composed of severalmainparts, viz., an outer shell I of a generally cylindrical form and aninner shell 2, also of cylindrical form, which inner shell is obviouslysmaller in both length and diameter than the 'outer shell I. The outershell has a closed head end 3, a closed lower end 4 and a basesupporting member 5. The inner shell 2 is also closed at its upper endby closure 6 and likewise. the bottom by closure 1. Bottom closure l isspaced a short distance from the y lower end of and within the lowerportion of inner shell 2. The inner shell extends upwardly from thebottom of the outer chamber, substantially coaxially therewith, so as toform an annular space between the walls of the inner and outer shellsand a cylindrical space Within the outer shell and above the innershell.

The generally cylindrical inner shell 2, with its two ends closed, formsa steam chamber 8 into which steam is admitted into theY upper portionof the steam chamber through uid inlet means, such as steam inlet pipe9. The bottom end 1 of this inner chamber 8 serves as one support forthesteam pipe 9, the latter being welded or otherwise rigidly attached in agas-tight manl. in the form of a lake.

ner with the end member 1. A web or plate member II) lis welded orotherwise attached to the upper end of the steam pipe 9 and to the innerwall of the steam chamber 8 as shown, for support of the steam pipe 9.The bottom closure member 1 of the steam chamber 8 is an inwardly curvedmember so as to provide a sump for drainage of condensate through adrain pipe II.

'I'he head end closure member 3 of the outer shell I has vapor outletmeans, such as flanged opening I5, adapted to take a anged pipe forconveyance of vaporized material from the evaporator. A liquid inletmeans, such as tube I6, extends through the side wall of the outer shellnear the head end and terminates in a short section of pipe Il at rightangles to the inlet tube IE in such a manner as to discharge in adownward direction any material entering the pipe I1. The upper end ofthis pipe is of course closed. f The inlet tube I6 may be welded inplace or may be threadedly attached to a collar member I8 which may bewelded or otherwise rigidly attached to the shell 3.

To the head end of the inner steam chamber 2 is attached a smallcircular plate I9 as shown and arranged in such a manner as to be in thepath of flow of liquid exiting from the inlet pipe section I'i. Aroundthis plate I9 and somewhat greater in diameter is a retainer means, suchas collar 20, which is welded to the head end member 6 of the steamchamber. This collar member is intended to retain vliquid to beevaporated which enters through the inlet tubes I6 and I1 As long asonly a very small volume of volatile liquid is added it is for the mostpart completely retained within the limits of this ringmember 20. Underthese conditions evaporations of small amounts of liqueed gases can beaccomplished without raising the temperature of the vapors formed to agreat extent. However, when a larger volume of liquid is to beevaporated, the liquid overflows from the ring 20 and runs down thesides of the steam chamber 2.

Since most such liquids do contain at least traces o! higher boilingmaterials, a sump ZI havlng fluid outlet means, such as drain 22, isprovided !or their removal.

The water condensate outlet II, similar to the `steam inlet pipe 9, isnot welded nor otherwise attached to the base end member 4 because ofthermal expansion considerations.

An auxiliary inlet means, such as liquid inlet 2l, is provided near thebase of the evaporator for use under heavy load conditions.

An opening 24 is provided in the outer shell for inserting a reliefvalve, not shown. for safety purposes.

An exterior steam jacket 25 is provided for use under heavy loadconditions especially in cold weather. This exterior jacket is formed byan outer cylindrical shell 26, end closure means, such as members 30,and the outer shell I of the evaporator proper. Two or more steam inletopenings 28 are providedat the upper end of the jacket as shown, while,a condensed steam or water outlet opening 29 is provided at the lowerend thereof.

For installing such an evaporator for use in vaporizing such materialsas liqueed petroleum gases, the base of the evaporator may be fixed toany desired foundation or other support as desired, and it shouldpreferably be rigidly attached to such a support.

A pipe or tube from a source of liqueed petroleum gas, as an undergroundtank, etc., not shown, branches, and the main branch is attached toinlet member I8, while the secondary branch is connected with the inletopening 23. These branch lines are not shown. for reasons of simplicity.A popoif or other type of relief or safety valve is fitted to opening24.

to steam pipe 9. Sump drain 22 is attached to such disposal as desiredfor removal of heavy hydrocarbon ends. Pipe II and opening 29 areconnected to pipes for water or condensed steam disposal.

Outlet I5 from the evaporator space is attached to a gas main fortransfer of vaporized gas to points of disposal.

Liquefied petroleum gases are usually transported and stored underconsiderable pressure. Accordingly, a pressure reducing valve should beinstalled in the liquid feed line just outside the inlet connection I8.In like manner a pressure reducer should be installed so as to controlpressure of liquid entering the vaporizing chamber through inlet 23. Ifdesired, a pressure reducing valve may be installed in the main feedline prior to its branching to points I8 and 23.

Liquefied petroleum gas at either storage tank or reduced pressure isintroduced through inlet tube I6 into my evaporator, and during periodsof small gas consumption all the liquid may be vaporized on top of theinternal steam chamber. At slightly higher rates of flow, some liquidmay overflow the wall 2U and run down the side of the steam chamber.Such liquid is thenv vaporized by heat from the sides of the steamchamber or by contact with superheated vapor which is rising from thebottom of the vaporizing chamber. This intimate contacting of liquid andvapors in the vaporization chamber results in the overall vaporizationof the liquid petroleum gas at substantially the boiling point of thematerial at the pressure at which it is being vaporized. The annularspace comprising the vaporization chamber is intended to be suiiicientlylarge as to permit gas rise to the exit point of the chamber withoutentraining liquid. l

The outer steam jacket may be supplied steam independently from theinner .chamber 8 so that it may be used or not used as desired. Duringthe summer season or periods of moderate gas consumption it may not benecessary to use this outer Jacket and therefore heat loss by radiationto the atmosphere can be reduced and also this will permit additionalcontrol of the superheat of the vaporized gas.

The pipe section I1 at the discharge end of the liquid inlet pipe I8 isintended to reduce the velocity of the liquid to be vaporized in theevent the liquid has experienced a pressure reduction and volumeincrease due to vaporization at the point of pressure reduction. Thepipe l1 points downward so as to direct the ow of inlet material towardthe vaporization chamber 8. The other liquid inlet 23 is provided nearthe bottom of the vaporizing chamber for use in the event there is anytendency for the vaporized gas to prevent downflowing liquid from withinring 28 from reaching the bottom of the heat exchanger. A perforateannular ring 3|, at a level not higher than closure 1, provides anannular space in the bottom of the vaporization chamber which space isnot heated by steam from either the steam chamber 8 or the steam jacket25. This annular space forms a sump to serve as a collecting space forunevaporated heavy hydrocarbon ends which may then be withdrawn throughpipe 22 for disposal.

It is especially important that these heavy ends not be heated,especially during periods of very low gas consumption, for it allowsthem to be separated and withdrawn from the system. If heated, theyvaporize and are withdrawn with the other gases and may ultimatelycondense and accumulate at undesirable points along the gas distributionsystem.

The materials of construction of my evaporator as herein disclosed maybe selected from among those commerciably available, but I have foundthat ordinary steel plate stock serves well. Fittings such as thethreaded openings should preferably be welded into the evaporator bodyas illustrated.l

The particular dimensions and relative size of the constitutent parts ofthe evaporator may be varied by those skilled in such art to solve theparticular evaporizatin problem at hand.

While I have described my invention as being particularly adapted forthe evaporation of liquefied petroleum gases, its use is not necessarilylimited to this application since it operates equally as well forquantity evaporation of any liquefied gases.

It will be obvious to those skilled in the art that many modificationsand alterations of my evaporator may be made and yet remain within theintended spirit and scope of my invention.

Having disclosed my invention, I claim;

l. An evaporator comprising in combination a closed outer shell; aclosed inner shell, being shorter and smaller than said outer shell,extending from the bottom of and substantially coaxially with said outershell; heat exchange medium inlet means extending into said inner shellto a point in the upper portion thereof; heat cylindrical shell issurrounded by a further cyline drical shell forming an annular spacetherebetween, said further cylindrical shell being shorter in lengththan said outer shell; closure means attaching the ends of said furthercylindrical shell to said outer shell in substantially a fluid tightmanner; and inlet and outlet openings in said further cylindrical shellfor inlet and outlet of a heating medium.

3. An evaporator comprising in combination a substantially verticallydisposed closed outer shell; a closed inner shell, being shorter andsmaller in diameter than said outer shell, extending from the bottom ofand substantially coaxially with said outer shell so as to form a spacebetween the side walls of said inner and outer shells and between thetops of said inner and outer shel1s; liquid retainer means on the top ofsaid inner shell; fluid inlet means adapted so as to convey hot fluidheat exchange medium into the upper portion and against the upper end ofsaid inner shell; fluid outlet means adapted so as to convey said heatexchange medium from the lower portion of said inner shell to the eX-terior of said outer shell; liquid inlet means in said outer shell,adapted so as to convey liquid downwardly against the upper end of saidinner shell and into said liquid retainer means; and vapor outlet meansin the upper portion of said outer shell.

4. An evaporator comprising in combination an upright closed cylindricalouter shell; a closed cylindrical inner shell, being shorter and smallerin diameter than said outer shell, extending from the bottom of andsubstantially coaxially with said outer shell so as to form asubstantially annular space between the walls of said inner and outershells and a substantially cylindrical space within said outer shell andabove said inner shell; liquid retainer means comprising a collar memberaiixed to the outside of the top of said inner shell; iluid inlet meansadapted so as to convey hot uid heat exchange medium upwardly throughsaid inner shell into its upper portion and against its upper end; uidoutlet means adapted so as to convey said heat exchange medium from thelower portion of said inner shell to the exterior of said outer shell;liquid inlet means in the upper portion of said 4o outer shell, adaptedso as to convey liquid downwardly onto the upper end of said inner shelland into said liquid retainer means; and vapor outlet means in the upperportion of said outer shell.

5. An evaporator comprising in combination an upright closed cylindricalouter shell; a closed cylindrical inner shell, being shorter and smallerin diameter than said outer shell, extending from the bottom of andsubstantially coaxially with said outer shell so as to form asubstantially annular space between the walls of said inner and outershells and a substantially cylindrical space within said outer shell andabove said inner shell, the bottom closure in said inner shell beingspaced a short distance from the lower end of said shell; liquidretainer means comprising a collar member aiiixed to the outside of thetop of said inner shell; fluid inlet means adapted so as to convey hotfluid heat exchange medium upwardly through said inner shell into andagainst its upper portion; fluid outlet means adapted so as to conveysaid heat exchange medium from the lower portion of said inner shell tothe exterior of said outer shell; a first liquid inlet means in theupper portion of said outer shell, adapted so as to convey liquidagainst the upper portion of said inner shell and into said liquidretainer means; a second liquid inlet means in the lower portion of saidouter shell; perforate closure means in the annular space between saidrst and second shells, positioned on a level at least as low as saidbottom closure in said inner shell and below the level of said secondliquid inlet means; liquid outlet means in the lower end portion of saidouter shell below said perforate closure means; and vapor outlet meansin the upper portion of said outer shell.

6. The evaporator of claim 1 wherein the outlet end of said heatexchange mediuminlet means in the upper portion of said inner shellopens toward the upper end of said inner shell.

OWEN L. GARRETSON.

REFERENCES CITED The following references are of record in the le ofthis ,patentz UNITED STATES PATENTS

1. AN EVAPORATOR COMPRISING IN COMBINATION A CLOSED OUTER SHELL; ACLOSED INNER SHELL, BEING SHORTER AND SMALLER THAN SAID OUTER SHELL,EXTENDING FROM THE OUTER SHELL; HEAT EXCHANGE COAXIALLY WITH SAID OUTERSHELL; HEAT EXCHANGE MEDIUM INLET MEANS EXTENDING INTO SAID INNER SHELLTO A POINT IN THE UPPER PORTION THEREOF; HEAT EXCHANGE MEDIUM OUTLETMEANS COMMUNICATING BETWEEN SAID INNER SHELL AND THE EXTERIOR OF SAIDOUTER SHELL; LIQUID INLET MEANS IN THE UPPER PORTION OF SAID OUTER SHELLAND EXTENDING DOWNWARDLY TO A POINT SPACED ABOVE THE TOP CENTRAL PORTIONOF SAID INNER SHELL; AND VAPOR OUTLET MEANS IN THE UPPER PORTION OF SAIDOUTER SHELL.